Bimolecular Reactions of Trapped Ions. VI. Ion–Molecule Reactions Involving CH5+ and C2H5+

Abstract

The ion–molecule reactions in mixtures of methane with the polar molecules dimethyl-d6 ether, ethylene-d4 oxide, acetaldehyde-d4, acetone, and acetonitrile have been studied using the trapped-ion technique. The CH5+ and C2H5+ ions produced by ion–molecule reactions in methane react rapidly (predominantly by proton transfer) with the polar molecules; the rate coefficients range from 1.98 × 10−9 cm3 molecule−1 s−1 (C2H5+ + C2D4O) to 5.26 × 10−9 cm3 molecule−1 s−1 (CH5+ + (CH3)2CO). The rate coefficients are much larger than those predicted from ion – induced dipole interactions only indicating that ion–dipole interactions play a large role in the collision process.Rate coefficients for reaction of CH3+ and CH4+ with the polar molecules also have been measured. Most of these also are larger than predicted from ion – induced dipole interactions indicating in this case as well substantial effects due to ion–dipole interactions.